machinevisiontoolbox.Image.gamma_encode

Image.gamma_encode(gamma)

Gamma encoding

Parameters:

gamma (str, float) – gamma value

Returns:

gamma encoded version of image

Return type:

Image

Gamma encode the image. This takes a linear luminance image and converts it to a form suitable for display on a non-linear monitor. gamma is either the string ‘sRGB’ for IEC 61966-2-1:1999 or a float:

\[\mat{Y}_{u,v} = \mat{X}_{u,v}^\gamma\]

Example:

>>> from machinevisiontoolbox import Image
>>> img = Image(np.arange(8)[np.newaxis, :])  # create grey step wedge
>>> img.gamma_encode('sRGB').disp()
<matplotlib.image.AxesImage object at 0x7f2acbd35280>
Note:

  • gamma is the reciprocal of the value used for gamma decoding

  • Gamma encoding is typically performed in a camera with \(\gamma=0.45\).

  • For images with multiple planes, the gamma encoding is applied to all planes.

  • For floating point images, the pixels are assumed to be in the range 0 to 1.

  • For integer images,the pixels are assumed in the range 0 to the maximum value of their class. Pixels are converted first to double, processed, then converted back to the integer class.

References:

  • Robotics, Vision & Control for Python, Section 10.2.7, 10.3.6, P. Corke, Springer 2023.

Seealso:

gamma_encode colorspace